Advances in cardiovascular surgery during the past two decades have created a demand for artificial prostheses to replace and repair portions of the human vasculature which become damaged due to disease and injury. The ideal vascular prothesis should be impervious to blood loss even in the heparinized patient on cardiopulmonary bypass. The prothesis should also have good surgical handling characteristics, have low flow surface thrombogenicity (i.e., inability to activate platelets, white blood cells and factor XII), be free from embolic complications, have no adverse effect on blood, have at implantation or develop thereafter features that encourage outer wall healing by fibroblastic ingrowth from the perigraft tissues, and have intrinsic strength adequate for indefinite dimensional stability.
In addition, it would be desirable to provide a prosthesis which remains pliable and preserved in a relatively dry state for an extended period to enhance its convenience to the surgeon.
Prior art prostheses have attempted to fulfill these essential requirements by providing polyester knit grafts which have been subjected to preclotting by treatment with the patient's blood to provide a fibrin matrix to seal the interstices of the graft. This method is disadvantageous in that it requires additional time to be expended by the surgeon as well as utilization of a volume of the patient's blood.
Other prior art grafts include those that are pretreated with gelatin to reduce the implantation porosity and to obviate the necessity for preclotting. Guidoin et al. (J. Biomedical Materials Research 18, 1059-1072, 1984) suggest utilizing polyester prostheses fabricated from polyethylene terephthalate by treating them with cross-linked albumin. The method disclosed by Guidoin et al. teaches the immersion of the prosthetic graft into a cross-linking solution of albumin and glutaraldehyde. Jordan et al., Surgery 53:1, 45 (1963) disclose impregnating Dacron.TM. vascular grafts with gelatin. Humphries et al. Surgery 50:6, 947 (1961), collagen-impregnated Dacron.TM. arterial prostheses. In the dry state, all of these prior art grafts are hard and cannot bend.
These and other prior art prostheses having cross-linked protein fail to provide sufficent impermeability at the time of implantation. This is due to the fact that at least some of the interstices of the grafts are void or incompletely filled. Consequently, the surgeon is faced with implanting arterial grafts which have a tendency to leak, which results in undesirable blood loss.